Spark-plug



G. L. HERZ.

SPARK PLUG. APPLICATION FILED JAN- II. 1918.

Patented Mar. 8, 1921.

' the boron member of the insulator comprises a mica -.The outer member 6 mayrbe of any suit UNITED STATES- P'A'TE T OFFICE.

" eusravn n. HEBZ, or NEW Yonmn. Y. a

' SPA-BK- Application @1011 January 17 To all whom it may ncern:

Be it known that I GUSTAVE L Hnnz,-a citizen of the United tates, and residentof h of Manhattan, in the city and State of rew York, have invented a new and useful Improvement in Spark-Plugs, of which the following is a specification.

' In the manufacture of spark plugs having mica insulators it has been practically impossible to secure an insulator which would not leak or break down under the severe usage to which spark plugs are sub ected m use, this leakage especia 1y happenin at the inner exposed end of the insu ator. his defect came from the inability to properly compress the mica washers at the'shouldered inner end of the center electrode and maintain them under proper compression.

.The object of m invention is to provide a mica insulator aving a' stack of mica I washers and an independent member comosed of a group ofrnica washers suitably ound together, as, for instance, byan eyelet. I

Another obiect of my invention is more particularly to roduce a mica insulator in which the liability of leakage, especially at the inner exposed end of the insulator, is obviated by the introduction of-the independent bound group of mica washers at this exposed portion.

A stlll further object of my invention is to provide means for equalizing the pres sure on the mica tube and mica washers by y 'the introduction of means bearing against the outer end of the mica tube;

A practical embodiment of my mvention is represented in the accompanying drawings, in which- A igure 1 represents in side elevatlonmy improved mica insulator mounted on the center electrode of aspark plug,

Fig. 2 is a longitudinal, through the same, and

Fig. 3 is a longitudinal central section cntral section I through the eyeletedgroup of mica washers before being placed inf-position in the insu; lator.

The center electrode 1 of the spark plug has a shouldered anger end 2 and a screw threaded outer\ end 3.' The intermediate tube 4 and the. body 5 of mice. washers.

he inner member ableinsula'ting material.

Specification of Letters Patent. v

, 1918-. seriai'm. 212,266.

i that point which is'subject to the rave.

Paton tedMar. 8 1921.v

comprises an independent group 7 of mica I washers bound together in the stance by the e elet 8. 1

present ini The means or maintaining the insulator in position with the bound group 7 of mica -washers tightly engaging the shouldered inner end 2 of the center electrode is shown as a nut 9 engaged with the screw threaded outer end 3 of theelectrode.

A metal washer 10'may be locatedbetweenthe outer member 6 and the nut 9.

The outer member 6 may be provided with a centrally arranged recess 11 into which the outer end of the mica tube 4 extends and any means, such, for instance, as a coil spring 12 may be located between the bottom of the recess lland the outer end of the mica tube 4 to compensate for differences in compression of the'stack of wash ers and the tube.

Themetal eyelet 8 of the group 'of mica washers snugly fits the center electrode 1 andthere are, preferably provided annular e grooves 13, 14;, formed in the bases ofthe inner and outer'flanges 15, 16, so that when the parts are forced-into position on the electrode, the mica washers on the eyelet will not be forced outwardly with a tendency to split or break, by the endwise pressure on the eyelet. The flanges 15, 16, overlap the outer and inner faces of thegroup 7 i of mica washers and form, in (the present instance, bearings for the mica tube 4; and shouldered-end 2 of the electrode. The prov1s1on of this independent member at the exposed lnner end of the insulator serves to obtain an absolutely non-leakable section -trode it is understood that the insulator is ouldered end of theelecsubjected to endwise pressure against the 'shouldeiedjnn'er end of the electrode by anysuitab'le means and the nut 9 is usedto maintain the members lntheir compressed state.

It has been found feasible to make the metal washer 10 and the eyelet 8 of soft metal, such, for instance, as copper.

It is evident that various changes may be resorted to in the form, construction and arrangement of the several parts without departin from the spirit and scope of my invention; hence 1 do not wishto limit myself strictly to the structure herein shown and described, but

What I claim is 1. In a spark plug, a mica insulator including a stack of mica washers, an independent group of mica washers forming an uninterrupted continuation of said stack at the inner exposed end of the insulator, and an eyelet for binding the group together.

2. A mica insulator member composed of a group of mica washers and an eyelet for binding them together, said eyelet having an annular groove at the base of one of its flanges, for the purpose set forth.

3. A mica insulator member composed of a group of mica washers and an eyelet for binding them together, said eyelet having annular grooves at the bases of its flanges, for the purpose set forth.

1. In a spark plug, a mica insulator comprising independent outer, inner and intermediate members, the inner member being composed of a separately bound group of mica Washers.

5. In a spark plug, a mica insulator comprising an outer member having a recess, an inner member and an intermediate member comprising a stack of mica washers and a ing a shouldered inner end, a mica insulator having anindependent inner member composed of a separately bound group of mica washers and means maintaining the insulator in position on the electrode with the inmembers, said intermediate member comprising a stack of mica washers and a mica tube bearing against the inner member and projecting into the outer member, means bearing against the outer end of said tube and means maintaining the insulator in position on the electrode with the inner member tightly engaging said shouldered inner end of the electrode.

8. In a spark plug, a center electrode having a shouldered inner end, a mica insulator having an inner member composed of a group of mica washers and an eyelet having flanges overlapping the opposite faces of the group, the inner flange projecting beyond the shouldered innerend of the electrode.

9. In a spark plug, a center electrode having a shouldered inner end, a mica insulator having a mica tube and an inner member composed of a group of mica washers and an eyelet having flanges overlapping the opposite faces of the group, said flanges forming bearings respectively for the inner end of the mica tube and the shouldered inner end of the center electrode.

In testimony, that I claim the foregoing as my invention, I have signed my name, this eleventh day of January, 1918.

GUs'rAvE L. HERZ. 

